3M coated 244D flap wheel uses aluminum oxide as the abrasive material and has a diameter of 1 in. 3M incorporates this aluminum oxide material into the flap wheel forming a grit of 60. All abrasive products that rotate or spin, such as the ones in this category, have a maximum speed at which you can run them. This 3M flap wheel can be run at a maximum speed of 30000.